Water spray over transfer mechanism for cooling chars

ABSTRACT

Char made from lower ranked coals in a horizontal chain grate coking furnace is discharged at the output end of the furnace into a laterally moving horizontal screw conveyor wherein it is quenched, fed laterally, and discharged into the top of a shaft furnace.

United States Patent 1191 Hagstrom 1 Oct. 1, 1974 [54] WATER SPRAY OVERTRANSFER 1,944,192 1/1934 Riddell 202/227 MECHANISM O COOLING CHARS2,997,427 8/1961 Mansfield 3,591,462 7/1971 Bretz 202/117 Inventor:Robert G. Hagstrom, Nashville,

Tenn.

Assignee: Peabody Coal Company, St. Louis,

Filed: Apr. 13, 1973 Appl. No.: 350,771

US. Cl 202/117, 202/227, 201/39 Int. Cl. .;.C10b 1/00, ClOb 39/12 Fieldof Search 202/227, 226, 230, 117,

References Cited UNITED STATES PATENTS 9/1918 McDonald 202/227 PrimaryExaminer-Wilbur L. Bascomb, Jr. Assistant ExaminerD. Sanders Attorney,Agent, or Firm-James H. Littlepage [57] ABSTRACT Char made from lowerranked coals in a horizontal chain grate coking furnace is discharged atthe output end of the furnace into a laterally moving horizontal screwconveyor wherein it is quenched, fed laterally, and discharged into thetop of a shaft furnace.

4 Claims, 2 Drawing Figures ATMOSPHERE EAIENTEDBBT 1 1 3.839, 1 5T FIGIATMOSPHERE WATER SPRAY OVER TRANSFER MECHANISM FOR COOLING CHARS RELATEDAPPLICATIONS Whitten and I-lagstrom, PRODUCTION OF ACTI- VATED CHARUSING A MOVING GRATE STO- KER, Ser. No. 130,737 filed Apr. 2, 1971, nowabandoned.

BACKGROUND OF THE INVENTION In utilizing the method disclosed in theWhitten and I-Iagstrom application, supra, the coal, after being charredin a hot carbonizing furnace nearly to the point of completedevolatilization, was dropped off the end of a horizontally moving chaingrate into the top of a shaft furnace. While this method is successfulwith bituminous or higher ranked coals, it was found that char made fromlower ranked materials such as peat, lignite, or brown coal and some ofthe lower volatile subbituminous coals have such extensive surface areathat it would undergo excessive oxidation in transit from the cokingfurnace to the shaft furnace. This was due at least in large part to thepresence of small amounts of oxygen in the system.

Another advantage in this over the former system is in the eliminationof what may be called a packing factor. As the char moved downwardlythrough the shaft furnace, it was quenched with cool inert gas which wasswept through it. Somehow or other, the char would pack so that thequenching gases were prevented from reaching parts of the mass, so thatwhen this mass was subsequently exposed to the atmosphere, it tended toreignite.

According to the present invention, it is intended now to provide, atthe end of the coking oven in which the coal is charred, a hopper intowhich the char drops from the oven grate, and a water spray forquenching the char as it drops into the hopper. In the bottom of thehopper is a screw conveyor which feeds the hot, wet char into the top ofa shaft which constitutes a holding tank. Water is sprayed onto the charin the top of the shaft and a suitable feeder discharges the coal charfrom the bottom of the shaft.

These and other objects will be apparent from the followingspecification and drawings, in which:

FIG. 1 is a diagrammatic vertical cross section taken lengthwise of theapparatus; and,

FIG. 2 is a diagrammatic vertical cross section taken transverselythrough the end of the apparatus.

Referring first to FIG. 1 of the drawings, the material to be charredsuch as peat, lignite, brown coal, and possibly one'of the lowervolatile sub-bituminous coals is fed from a storage bin through a scale12 and hopper inputs 14 ofa hot carbonizer furnace 16 (see MansfieldU.S. Pats. Nos. 3,434,932 and 3,434,933 for further details of this typeof coking furnace) in which the material is spread onto a horizontallymoving chain grate 18 by means of a spreader gate 20 to form a bed 22.The chain grate runs over end sprockets 23, 24 in the directionindicated, the sprockets being conventionally driven and supported byshafts and bearings, not shown, and beneath the top run of the chaingrate is a zoned airbox 26. As the bed passes over the airbox zones(zones 16, for example), various amounts of air and steam may be zonefed upwardly through the bed and hot combustion by-product gases may bedowndrafted through the bed. The net result being that the material ischarred as it moves through the furnace and as the char drops off theend of the grate run which is at the output end of the furnace. It isalmost completely devolatilized, so hot and with so much surface areathat it would immediately oxidize if exposed to air. To prevent this,the following are provided:

Disposed within the housing of the furnace so as to catch the char asthe latter drops off the end of the grate run is a hopper 28 in thebottom of which runs a screw conveyor 30. As the hot char drops towardsand into the hopper, it is sprayed with water issuing from spray jets32. Steam issues upwardly via stack 33 and the wet char is screwedlaterally through a restricted passage 34 into the top end of ashaft-like holding tank 36 from the bottom of which the then cooled charis discharged through a suitable air-lock feeder 38.

As the wet char enters the top of holding tank 36, it is again sprayedwith water issuing from suitable jets 40. The steam resulting from thisspraying, as well as from the water still in the char from the previousspraying, exhausts through the char as the latter is screwed through therestricted passage 34, whereupon it mingles with the steam and othergases issuing from the char in the hopper and exhausts through the stack33. Thus, no air can follow the char into the holding tank. By adjustingthe amounts of spray water issuing from jets 32 and 40, a carbon/waterratio can be established such as to produce adequate cooling of the charwhile at the same time producing a char which is reasonably dry.

This process cools high surface area char rapidly below the ignitionpoint in the absence of any oxidizing gases and greatly enhances fixedcarbon recovery without materially increasing the ash content of thechar. Since the sprayed water cools the char and is vaporized during thecooling period, an essentially dry char is produced; and, by the use ofthis system, there is no infusion of air from leaks or dumping grates atthe critical times and places where the danger of oxidation are mostserious.

I claim:

1. In an apparatus for producing char comprising,

a carbonizer furnace having laterally disposed input and output ends,means for feeding material to be charred to the input end of thefurnace,

endless chain grate means for conveying the material horizontallythrough the furnace from the input to the output ends thereof,

and means for feeding air in controlled amounts through the material asthe latter is conveyed through the furnace so as to create limitedcombustion sufficient to raise the temperature of the materialsubstantially devolatilized the same and produce thereof a hot char,

the improvement which comprises a horizontal trough disposed below theoutput end of the furnace in position to receive the hot char freelyfalling from the chain grate at the output end of the furnace,

said trough terminating in an open end,

a holding tank having an upper end portion, the open end of the troughterminating in the upper end portion of the holding tank, whereby charissuing from the open end of said trough falls by gravity into saidholding tank,

conveyor means in said trough for feeding the char from the trough tothe tank,

water spray means for spraying water onto the char as the latter isreceived into the trough from the furnace; and means for discharging thechar from the bottom of the holding tank.

2. The improvement recited in claim 1, and water spray means forspraying water onto the char as the latter is fed into the holding tankfrom the trough.

3. The improvement recited in claim 1, and means providing a restrictionin the passage for the char between the trough and the holding tank saidconveyor being a screw conveyor running from the bottom of the trough tothe upper portion of the holding tank, a convolution of said screwconveyor occupying said restrict1on.

4. In combination with a carbonizer furnace for producing char,including means providing a furnace housing having a free-falling chardischarge,

a horizontal trough for receiving free-falling char from said discharge,said trough having an open end,

a holding tank having an upper end portion, the open end of the troughterminating in the upper end portion of the holding tank, whereby chardischarged from the open end of the trough falls freely into saidholding tank,

conveyor means for feeding char through said trough to said tank,

means for spraying water on said char as the latter falls freely intosaid trough,

and means for spraying water onto the char as the latter falls freelyinto the holding tank from the trough.

1. In an apparatus for producing char comprising, a carbonizer furnacehaving laterally disposed input and output ends, means for feedingmaterial to be charred to the input end of the furnace, endless chaingrate means for conveying the material horizontally through the furnacefrom the input to the output ends thereof, and means for feeding air incontrolled amounts through the material as the latter is conveyedthrough the furnace so as to create limited combustion sufficient toraise the temperature of the material substantially devolatilized thesame and produce thereof a hot char, the improvement which comprises ahorizontal trough disposed below the output end of the furnace inposition to receive the hot char freely falling from the chain grate atthe output end of the furnace, said trough terminating in an open end, aholding tank having an upper end portion, the open end of the troughterminating in the upper end portion of the holding tank, whereby charissuing from the open end of said trough falls by gravity into saidholding tank, conveyor means in said trough for feeding the char fromthe trough to the tank, water spray means for spraying water onto thechar as the latter is received into the trough from the furnace; andmeans for discharging the char from the bottom of the holding tank. 2.The improvement recited in claim 1, and water spray means for sprayingwater onto the char as the latter is fed into the holding tank from thetrough.
 3. The improvement recited in claim 1, and means providing arestriction in the passage for the char between the trough and theholding tank said conveyor being a screw conveyor running from thebottom of the trough to the upper portion of the holding tank, aconvolution of said screw conveyor occupying said restriction.
 4. Incombination with a carbonizer furnace for producing char, includingmeans providing a furnace housing having a free-falling char discharge,a horizontal trough for receiving free-falling char from said discharge,said trough having an open end, a holding tank having an upper endportion, the open end of the trough terminating in the upper end portionof the holding tank, whereby char discharged from the open end of thetrough falls freely into said holding tank, conveyor means for feedingchar through said trough to said tank, means for spraying water on saidchar as the latter falls freely into said trough, and means for sprayingwater onto the char as the latter falls freely into the holding tankfrom the trough.